Air inlet damper apparatus

ABSTRACT

An air inlet damper apparatus for minimizing the entrance of outside air into a poultry house when the ventilation exhaust fans are running and the radiant tube heater is not operating. The apparatus has a housing with a passage and a coupling flange; a pin that spans the passage and divides the apparatus into a low pressure side and an outside high pressure side, where the low pressure side is in fluid communication with a blower supplying combustion air to the tube heater; a damper blade connected to the pin; a stop; and a means for controlling the damper blade. The controlling means is responsive to pressure. The damper blade pivotally opens away from the stop when there is a static pressure differential that is higher than the negative pressure created by the ventilation exhaust fans, or when the controlling means electromechanically actuates the damper blade.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The invention relates to an air damper apparatus, and more particularly to an air inlet damper apparatus for tube heaters that are operating in a building that has a negatively fluctuating pressure, wherein the air inlet damper apparatus prevents the entrance of outside air through a tube heater when the tube heater is not operating.

2) Prior Art

Over the last several years, there has been increasing utilization of tube heaters, and in particular radiant tube heaters for poultry houses. These are propane or natural gas-fired heaters in the shape of long tubular cylinders (pipes) that are usually hung near the ceiling of the house. Several variations of tube heater are available. Radiant heating has some advantages over forced air heat, as has been seen by the adoption of radiant brooders.

Typically, a tube heater is comprised of a burner housed in an enclosure connected to an emitter tube, which may be metallic. The length of the emitter tube varies from 10 to 80 feet. The heater is usually hung near the ceiling and sends radiant heat downward from the long radiant tubes. The emitter tube can run from side-to-side, as well as lengthwise, depending on the width of the building. In poultry houses, combustion air is usually drawn in from the loft space close to the ridge vents on the roof, and occasionally directly from the outside through the sidewall, through a fresh air intake spigot. The tube heater has a blower that pushes (or pulls depending on the design) excess carrier air and the products of combustion through the tube. Reflectors above the tubes are necessary to redirect the radiant energy from the top of the tube, back to the mass being directly heated. In the case of poultry houses, the floor and the birds. The combustion gases exiting the tube heater air are sufficiently free of pollutants that the heater normally exhausts to the inside of the poultry house.

The desired operating temperature of a poultry house is around 90° F. at floor level. Because of stratification of the air, the temperature closer to the heater will be higher. The poultry house is frequently ventilated using exhaust fans, which run on a timed cycle to remove harmful gases, such as ammonia, from the house air. While the exhaust fans are running, the pressure in the house is negative. In the winter, the outside air is typically substantially cooler than the air in the poultry house. When the heater is not in operation, the cold air cools the burner enclosure, and the high temperature, moist air in the poultry house forms condensation on the outside of the enclosure. The condensation, in turn, will run off onto the floor of the house, which is undesirable because it creates health concerns for the birds. In addition, the cold air entering the house will reduce the temperature, which increases the cycle frequency of the tube heater, thereby increasing the fuel consumption.

In the summer, when the exhaust fans cut on, the negative pressure in the poultry house draws hot outside air in through the tubes in communication with the air inlet spigots. This is undesirable because poultry houses use evaporative cooling pads on the side of the house to reduce the temperature. The effect of the introduction of hot air is that the exhaust fans will have to run longer to keep the temperature down, thus increasing the energy consumption.

What is needed is an air inlet damper apparatus that prevents cold air from entering the poultry house, except when the tube heaters are operating through the tube heater air inlet spigots in the winter. In the summer, the air inlet damper apparatus prevents hot humid air from entering the poultry house through the tube heater air inlet spigots. The air inlet damper apparatus creates a more stable temperature environment inside the poultry house and a more efficient utilization of energy. Furthermore, when the heater is operating the air inlet damper cannot restrict the intake of combustion air.

In addressing the problem, there are a number of limitations that add to the complexity of the problem. The air inlet damper cannot produce a pressure drop at the exhaust of the heater tube that is sufficient to prevent reliable operation of the air proving safety pressure switch. The environmental conditions inside the poultry house are such that any moving parts exposed to the inside of a poultry house will be directly exposed to dust and moisture, which will collect on the surface and damage or interfere with the normal operation of a motor or a moving component. Therefore, any exposed moving part must be located in the loft space above the main house space; however, there are access difficulties for both maintenance and installation in the loft. Electro-mechanical actuators, such as conventional damper assemblies, require electric power to operate the motor. Electro-mechanical actuators must be activated prior to operation of the heaters in order that the air proving safety pressure switch at the heater will sense the correct pressure to enable the operation of the heater. To operate the electromechanical actuator, an additional circuit will be required adding to the cost and complexity of the installation.

SUMMARY OF THE INVENTION

The invention is an air inlet damper apparatus that, except when an accompanying tube heater is operating, substantially prevents the entrance of outside air to the tube heater. The air inlet damper apparatus is comprised of: a housing having a passage; a pin that spans the passage and divides the apparatus into a low pressure side and an outside high pressure side; a damper blade connected to the pin; an inner housing stop; and a means for controlling the damper blade, wherein the controlling means will allow combustion air to pass when the heater is operating. The damper blade pivotally opens to allow combustion air to pass when the controlling means is pressure or mechanically actuated. The damper blade allows air to be freely drawn through the passage of the apparatus. The air inlet damper apparatus is operationally positioned in an air inlet spigot supplying combustion air to the tube heater. The tube heater has a blower that either pushes or pulls combustion gases through the combustion chamber.

The invention, furthermore, is a combination tube heater and air inlet damper apparatus, where the combination is in a building equipped with one or more exhaust fans, where the combination is comprised of: the tube heater with a blower for bringing in outside combustion air through the air inlet damper apparatus, where the apparatus has a damper blade and a controlling means. The controlling means substantially prevents the negative pressure inside the poultry house from pulling air from outside through the air inlet spigot and into the conditioned space within the house.

Operationally, it is desired that there be a minimal amount of heat loss because the more heat that is lost, the greater the cost of fuel to heat the building

In the broadest sense, the present invention refers to an air inlet damper apparatus that prevents the uncontrolled intrusion of outside air.

In a further broadest sense, the present invention also refers to a combination tube heater and air inlet damper apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects will become readily apparent by referring to the following detailed description and the appended drawings in which:

FIG. 1 is a perspective view of an air inlet damper apparatus, wherein the damper blade is a butterfly blade having two half blades and the controlling means is a tension spring.

FIG. 2 is a perspective view of an air inlet damper apparatus, wherein the damper blade is a butterfly blade having two half blades and the controlling means is a solenoid actuated piston

FIG. 2 a is a cross-sectional view of the solenoid actuated air inlet damper apparatus of FIG. 2, wherein the solenoid has actuated the notched piston 41, which in turn causes the butterfly blade to open.

FIG. 2 b is a cross-sectional view of the solenoid actuated air inlet damper apparatus of FIG. 2, wherein the solenoid is at rest, and the spring 27 has returned the piston and the butterfly blade is closed.

FIG. 3 is a perspective view of an air inlet damper apparatus, wherein the damper blade is a center-rotated blade and the controlling means is a motor.

FIG. 4 is a perspective view of the air inlet damper apparatus shown in FIG. 1, which illustrates the opposing side of the apparatus.

FIG. 5 is a partially cutaway view of a tube heater having a blower that provides outside air to the combustion chamber of the tube heater, where the invented air inlet damper apparatus is in fluid communication with the tube heater via a duct. The reflector is not shown.

FIG. 6 is an end-on-view of an exhaust end of the tube heater illustrated in FIG. 5, where the tube heater is fitted with a reflector.

FIG. 7 is a partially cutaway view of a tube heater having a blower that pulls outside air into the combustion chamber of the tube heater, where the invented air inlet damper apparatus is in fluid communication with the tube heater via a duct.

FIG. 8 is a partially cutaway view of a poultry house having exhaust fans in the walls of the house, wherein radiant tube heaters are mounted in the rafters.

FIG. 9 is a schematic isometric view of an air inlet damper apparatus, wherein the housing is rectangular.

FIG. 10 is a perspective view of an air inlet damper apparatus that is similar to the damper in FIG. 1, wherein the damper blade is a butterfly blade having two half blades and the controlling means is a torsion spring.

DETAILED DESCRIPTION

The invention is an air inlet damper apparatus 10 for minimizing the entrance of air into a poultry house or similar building having a negative pressure. The negative pressure is typically produced by exhaust fans to ventilate the building. The apparatus is comprised of: a housing having a passage; a pin that spans the passage and divides the apparatus into a low pressure side and an outside high pressure side; a damper blade connected to the pin; an inner housing stop against which the dampening blade can form a seal; and a means for controlling the damper blade, wherein said controlling means is responsive to pressure. The damper blade pivotally opens away from the stop upon reaching a static pressure differential between the low-pressure side and the high-pressure side. The static pressure differential is based on a predetermined pressure differential, which is usually higher than the negative pressure effected by the exhaust fans, but less than the static pressure differential caused by a blower on a tube heater. Once the pressure differential has been attained, the air inlet damper opens allowing combustion air to be drawn through the passage of the apparatus with only a slight pressure drop.

The invention is optimally configured such that the means for controlling the damper blade enables the damper blade to start to open once a static pressure differential is reached, and continues to open enough to maintain an adequate supply of combustion air to be controllably drawn through the passage of the apparatus to maintain the desired fuel to air mixing ratio. Examples of controlling means are a tension spring, a torsion spring or an articulating member actuated by a pressure sensor. The springs are selected and tensioned so that a negative building pressure does not significantly cause the damper blade to be opened when the tube heater is not operating. The apparatus assures that the blower pulls substantially the same volume of combustion air, whether the exhaust fans are on or off.

The housing is preferably a cylindrical duct with a circular passage. The wall of the duct has a gasket around it which allows it to be inserted into the fresh air intake spigot and form a seal. Alternatively, the walls of the duct are terminated with at least one connecting element for coupling the apparatus to a duct, or an intake to a tube heater blower, or a tube heater combustion chamber. The connecting element is selected from the group consisting of a flange, or lip, or a neck for forming a joint, or a combination thereof.

The pin can be positioned in the center of the passage so that it substantially bisects the passage, or the pin can be located off to the side of the passage. In either case, the pin has an orientation that is substantially orthogonal to the longitudinal axis of the passage. When the pin is in the center, a preferred embodiment is a butterfly blade, where the blade is comprised of two half blades that independently pivot on the pin, rotating toward the low-pressure side of the apparatus. As the half blades pivot from closed to open, they move from a position where they occlude the passage and the two halves are collinear or slightly angled toward the high pressure side, to a position where the passage is almost entirely open and the two halves overlap each other. At least one torsion spring is mounted on the pin between the two half blades on the high-pressure side of the passage, so that the spring is compressed as the half blades rotate from closed to open. When closed, the two half blades rest against a stop that substantially seals the passage even when there is a negative pressure on the building. The stop preferably is comprised of a rubber gasket, where the rubber has good aging properties. Examples of such rubber include neoprene, silicone, EPDM or acrylic rubber.

Referring to FIG. 1, the air inlet apparatus 10 has a cylindrical metallic housing 12 with a center passage 16. The cylindrical metallic housing is terminated with at least one connecting element 14 that is a gasket for inserting into ducts. Bisecting the passage 16 is a pin 18 (vertical orientation as shown) that is substantially orthogonal to the axis of the passage 16, where the pin 18 defines a high-pressure side 34 and a low-pressure side 32 of the apparatus 10. An aluminum damper blade is hingedly attached to the pin 18 in the form of two half blades 20 a and 20 b. Two half blades, 20 a and 20 b, are pivotally attached to the pin 18. The half blades rest on a stop 22 when no combustion air is moving through the air inlet damper apparatus 10, and swing open toward the interior low-pressure side 32, only when combustion air is moving through the air inlet apparatus 10. The stop 22 prevents the half blades, 20 a and 20 b, from rotating toward the high-pressure side 34, so air can only flow through the passage from 34 toward 32. There is a single torsion spring that is attached to the half blades, 20 a and 20 b. The spring 24 is selected so that as the half blades 20 a and 20 b open further the spring is compressed, thereby creating greater pressure on the damper half blades 20 a and 20 b. The springs are selected so that there is sufficient pressure that when a negative pressure is generated on the building 52 by exhaust fans 50 (as shown in FIG. 8), the damper half blades, 20 a and 20 b, will remain substantially sealed, occluding the passage 16. The spring establishes a static pressure differential. Static, in that no air is moving. The stop 22 has a neoprene ring gasket 26 mounted in the stop 22, and when not open the perimeter edge of the half blades 20 a and 20 b rest against the ring gasket 26 forming a seal 28 (as shown in FIG. 4) that prevents combustion air from moving past the damper half blades 20 a and 20 b, so that air can only move in one direction.

FIG. 10 illustrates an inlet damper 10 that has a gasket 67 and a tensioning spring 34, which tightens when the damper blade 20 opens. The housing 12 for the inlet damper 10 need not be cylindrical, and FIG. 9 illustrates a rectangular housing 12.

In normal operation, the apparatus 10 is connected to an air intake side of a blower 42 providing combustion air for a tube heater 40. As shown in FIG. 8, the blower 42 pulls outside combustion air in through an air inlet spigot 44, which is then forced into a combustion chamber 46 where it is mixed and burned with a gaseous fuel 48. When the blower 42 is operating, the blower 42 creates sufficient negative pressure to open the damper half blades, regardless of whether the exhaust fans are on or off. The compression on the spring 24 increases when the damper blade opens, but not enough to operationally affect the performance of the tube heater 40. When the blower is not operating there is insufficient pressure drop to cause the air inlet damper apparatus to open, thus preventing combustion air from being drawn into the house causing cold spots and condensation.

FIGS. 2-3 illustrate embodiments of an air inlet damper apparatus, wherein the controlling means is electromechanical. The controlling means opens the damper when the tube heater is starting up, and closes the damper when the tube heater is not operating. Referring to FIGS. 2, 2 a, and 2 b, adjacent to the damper blade 20 is a piston 41 that is actuated by solenoid 43. When the solenoid is actuated, the piston slides to the left, as shown in FIG. 2 a, compressing spring 27. Notch 29 engages the two butterfly half blades, 20 b and 20 a, which cause the blades to pivot open. When the solenoid 43 is not actuated, the spring 27 causes the piston to slide back to the right, as shown in FIG. 2 b. The negative pressure in the building will cause the butterfly blades to close against stop 22. The return movement of the butterfly blades can be augmented by the addition of a torsion spring 25, as shown in FIG. 2, which enables the damper to be mounted such that the solenoid piston is on either the low-pressure side of the damper or the high-pressure side. FIG. 3 illustrates an air inlet damper apparatus, wherein the damper blade is a center-rotated blade and the controlling means is a motor. The motor 23 rotates a disc 47 that is connected to shaft 45. When the motor is actuated it rotates the disc 47, damper blade 20 opens, and torsion spring 49 is wound tighter. When the motor is not actuated, the torsion spring causes the disc to counter rotate, closing the damper. In general, the controlling means can also be comprised of an articulating member that is actuated by a device, wherein the articulating member rotates the damper blade.

The gaseous fuel is selected from natural gas, propane, butane or a combination thereof. The tube heater 40 produces radiant heat energy 90 (diagrammatically shown as dashed lines in FIG. 8), which is reflected downward from tube heaters 40 mounted in the loft 58, as shown in FIG. 8, as well as products of combustion, e.g., carbon dioxide and water vapor. Each tube heater has a reflector 60, as shown in FIG. 6, which focuses and directs the radiant energy 90, as shown in FIG. 8. The tube heater 40 exhausts through an exhaust pipe 62 to the inside of the building, poultry house 52. The radiant energy 90 is directed toward the floor. As shown in FIG. 8, the air inlet damper 10 is positioned in the air inlet spigot 44, which draws air in from the loft 58 near the vents at the ridgeline of the roof. Typically, poultry houses are 500 feet long, and there are 7 tube heaters. In the illustration, only 4 are shown.

As shown in FIG. 7, the blower 42 can be located on the exhaust end of the tube heater, and the outside combustion air is pulled in through the heater 40. Referring again to FIG. 8, the poultry house 52 typically has multiple tube heaters 40, each fitted with an air inlet damper apparatus 10 for preventing the entrance of cold air through the tube heater. In a typical scenario, the poultry house is 500 ft long, and there are 7 tube heaters, each approximately 40 ft long.

The descriptions above and the accompanying drawings should be interpreted in the illustrative and not the limited sense. While the invention has been disclosed in connection with the preferred embodiment or embodiments thereof, it should be understood that there may be other embodiments which fall within the scope of the invention as defined by the following claims. Where a claim is expressed as a means or step for performing a specified function, it is intended that such claim be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof, including both structural equivalents and equivalent structures. 

1. An air inlet damper apparatus for minimizing the entrance of outside air through a tube heater when the tube heater is not operating, said apparatus comprising: a housing having a passage; a pin that spans the passage and marks a divide of the apparatus into a low-pressure side and an outside high pressure side, where the low-pressure side is in communication with the tube heater; a stop; a damper blade connected to the pin; a means for controlling the damper blade; wherein said controlling means determines at what static pressure differential the damper blade opens away from the stop or when the controlling means actuates the damper blade.
 2. The air inlet damper apparatus, as claimed in claim 1, wherein the damper blade is a butterfly damper blade having two half blades and the pin is substantially located in the center of the passage.
 3. The air inlet damper apparatus, as claimed in claim 2, wherein the controlling means is a torsion spring on the low pressure side between the two half blades, where the torsion spring maintains that the half blades are closed when the tube heater is not operating, and the half blades open when the tube heater is operating.
 4. The air inlet damper apparatus, as claimed in claim 1, wherein the stop is on the inner housing, and against said stop the dampening blade can form a seal.
 5. The air inlet damper apparatus, as claimed in claim 1, wherein the controlling means is an articulating member that adjusts the damper blade.
 6. The air inlet damper apparatus, as claimed in claim 1, wherein the tube heater burns combustion gases comprised of a gaseous fuel and outside air, where the outside air is pulled in by a blower through a duct that connects the blower to the air inlet damper apparatus.
 7. The air inlet damper apparatus, as claimed in claim 6, wherein, when operating, said blower moves an effective volume of combustion air, regardless of the pressure at the tube heater exhaust.
 8. The air inlet damper apparatus, as claimed in claim 7, wherein, when said tube heater is operated in a building having exhaust fans, the exhaust fans produce a negative pressure in the building and, by extension, a negative pressure at the tube heater exhaust.
 9. The air inlet damper apparatus, as claimed in claim 8, wherein said building is a poultry house.
 10. The air inlet damper apparatus, as claimed in claim 8, wherein said building has multiple tube heaters in fluid communication with one or more air inlet damper apparatus.
 11. The air inlet damper apparatus, as claimed in claim 8, wherein said blower provides air to a tube heater combustion chamber.
 12. The air inlet damper apparatus, as claimed in claim 8, wherein said blower pulls outside air into a tube heater combustion chamber.
 13. The air inlet damper apparatus, as claimed in claim 4, wherein said stop has a rubber ring gasket.
 14. The air inlet damper apparatus, as claimed in claim 1, wherein said air inlet apparatus is in fluid communication with an air inlet spigot.
 15. The air inlet damper apparatus, as claimed in claim 1, wherein said tube heater is a radiant heater.
 16. The air inlet damper apparatus, as claimed in claim 1, wherein said controlling means is selected from a solenoid actuated piston, a motor and spring, and an articulating member, where the controlling means controls the position of the damper blade.
 17. The air inlet damper apparatus, as claimed in claim 1, wherein said housing is substantially cylindrical.
 18. The combination in a building of an air inlet damper apparatus, a tube heater, a ventilation exhaust fan, and a conditioning device for lowering the humidity of incoming warm outside air, wherein said air inlet damper apparatus minimizes the entrance of outside air that is not conditioned, said apparatus comprising: a housing having a passage; a pin that spans the passage and marks a divide of the apparatus into a low-pressure side and an outside high pressure side, where the low-pressure side is in communication with the tube heater; a damper blade connected to the pin; a stop; a means for controlling the damper blade; wherein said controlling means determines at what static pressure differential the damper blade opens or when the controlling means actuates the damper blade.
 19. The air inlet damper apparatus, as claimed in claim 18, wherein said exhaust fan is cycled on and off, and when on, generates a negative pressure in the building.
 20. A combination tube heater and air inlet damper apparatus, said combination comprised of: a tube heater with a blower for bringing in outside combustion air through an air inlet damper apparatus, where the apparatus has a damper blade and a controlling means, where the air inlet damper apparatus minimizes the entrance of outside air when the tube heater is not operating.
 21. The combination, as claimed in claim 20, wherein said air inlet damper apparatus is in fluid communication with an air intake of the blower.
 22. The combination, as claimed in claim 20, wherein said air inlet damper apparatus is in fluid communication with a combustion chamber of the tube heater. 